Measurement of charmonium production in PbPb collisions at sqrt(sNN) = 2.76 TeV with CMS

TL;DR

This paper reports CMS measurements of charmonium production in PbPb collisions at 2.76 TeV, revealing significant suppression of prompt and non-prompt J/psi, providing insights into quark-gluon plasma effects on heavy quark states.

Contribution

First measurement of non-prompt J/psi suppression in PbPb collisions at LHC energies, advancing understanding of in-medium b-quark energy loss.

Findings

Strong, centrality-dependent suppression of prompt J/psi.

First observation of non-prompt J/psi suppression in heavy-ion collisions.

Upcoming Psi(2S) measurements and double ratio analysis.

Abstract

The Compact Muon Solenoid (CMS) is fully equipped to measure hard probes in the di-muon decay channel in the high multiplicity environment of nucleus-nucleus collisions. Such probes are especially relevant for studying the quark-gluon plasma since they are produced at early times and propagate through the medium, mapping its evolution. CMS has measured the nuclear modification factors of non-prompt J/psi (from b-hadron decays) and prompt J/psi in PbPb collisions at sqrt{s_{NN}} = 2.76 TeV. For prompt J/psi with relatively high p_T (p_T=6.5-30 GeV/c), a strong, centrality-dependent suppression is observed in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. In the same kinematic range, a suppression of non-prompt J/psi, which is sensitive to the in-medium b-quark energy loss, is measured for the first time. Results from the 2010 data taking period are reported and an outlook on the 2011 data analysis will be given. In particular from 2011 data the Psi(2S) measurement is available and their double ratio respect to the J/psi in pp and PbPb will be shown.